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It is known that 19% of people ride public transport without paying for it. We talk to 75 people who have been on public transport in the last month. What is the probability that the sample proportion is more than 22%?

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Final answer:

To find the probability that the sample proportion is more than 22%, calculate the standard error of the sample proportion using the formula SE = sqrt((p*(1-p))/n), where p is the known proportion and n is the sample size. Then calculate the z-score using the formula z = (sample proportion - population proportion) / standard error. Finally, use the z-score to find the probability using the standard normal distribution table or a calculator.

Step-by-step explanation:

To find the probability that the sample proportion is more than 22%, we first need to calculate the standard error of the sample proportion. The formula for the standard error is:

SE = sqrt((p*(1-p))/n)

where p is the known proportion of people riding public transport without paying, and n is the sample size.

In this case, p = 0.19 and n = 75. Plugging these values into the formula, we get:

SE = sqrt((0.19 * (1 - 0.19)) / 75) ≈ 0.0435

Next, we can calculate the z-score using the sample proportion of 22%:

z = (sample proportion - population proportion) / standard error

Plugging in the values, we get:

z = (0.22 - 0.19) / 0.0435 ≈ 0.6897

Finally, we can use the z-score to find the probability using the standard normal distribution table or a calculator. The probability that the sample proportion is more than 22% is equal to 1 minus the probability of the z-score. Depending on the specific table or calculator you are using, you can look up the probability and subtract it from 1 to find the final answer.

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